1. Field of the Invention
The present invention relates to a thin and slim type spindle motor housing, and more particularly to a housing with a structural improvement and a fabricating method for easily fabricating the same by means of the improved structure.
2. Description of the Prior Art
Generally, a hard disc drive employed for a portable personal computer such as a notebook computer becomes more favorable as it gets thinner. Therefore, a motor for hard disc drive is also to be of a thin slim type spindle motor, and a motor housing for forming the thin and slim type spindle motor should be so low as shown in FIG. 1.
In view of the construction of housing 1, a disc part 12 has an outer circumference 12a of an optional thickness, a shaft hole 13 perpendicularly perforates through the center of disc part 12 for assembling a motor shaft 4, and a cylinder part 14 protrudingly installed upward around the periphery of shaft hole 13 for the purpose of assembling of a stator 5 and inserting a bearing 6. An upper jaw 14a is formed to the lower end of the outer periphery of cylinder part 14 to sustain stator 5.
A flange part 11 extends from outer circumference 12a of disc part 12 to be thinner than disc part 12 in a manner to extend at the upper thickness portion of outer periphery 12a for making the bottom plane of flange part 11 place on the upper plane of a PCB substrate 7.
The most important part in assembling as described above is, as shown in FIG. 2, the bottom plane of flange part 11, which becomes a reference plane. Besides, shaft hole 13 for tightly fitting with motor shaft 4 therethrough, upper jaw 14a for sustaining stator 5, outer circumference 12a of disc part 12 and so on should be precisely fabricated.
Also, in considering the fabricating process of the foregoing housing, a pre-processing is performed via a molding method such as a die casting for forming overall configuration at a time and then a cutting processing is performed upon portions that require precision tolerance via a lathe, etc.
The most serious problem in fabricating the housing is to perform a chucking operation more than three times when the parts requiring the precision tolerance are subjected to the cutting process by means of the lathe.
For example, referring to FIG. 3A, after performing the first chucking for temporarily chucking the outer circumference side of unprocessed disc part 12, the upper plane of flange part 11, cylinder part 14 and upper jaw 14a of cylinder part 14 are subjected to a rough-cutting process.
Successively, cylinder part 14 of opposite side is secondarily chucked as shown in FIG. 3B. Then, the bottom plane of flange part 11 and outer circumference 12a, which should be precisely fabricated because of being the reference plane, are fabricated.
After outer circumference 12a of disc part 12 is subjected to the normal chucking again as shown in FIG. 3C, the upper plane of flange part 11, cylinder part 14 and upper jaw 14a of cylinder part 14 are precisely fabricated.
The reason of performing the chucking thrice is in that cylinder part 14 is to be necessarily chucked while the outer circumference 12a of disc part 12 is processed, but neither cylinder part 14 even nor outer circumference 12a of disc part 12 is precisely processed yet. For this reason, the precise fabricating in the sequence of the first chucking of chucking disc part 12, the second chucking of chucking cylinder part 14 and the third chucking of chucking disc part 12 should be performed.
The conventional housing structure described as above involves the drawback in that, because of being difficult to separately provide the portion which is to be chucked at the bottom plane side of flange part 11 of housing 1, the bottom plane of flange part 11 being the reference plane and shaft hole 13 cannot be simultaneously processed, thereby processing the opposite side in advance and then reversely turning it to chuck for performing the processing again. Due to this fact, the verticality of the reference plane of flange part 11 with cylinder part 14 and that of the reference plane of flange part 11 with shaft hole 13 cannot be assured.
In some cases, despite that outer circumference 12a is low, if the chucking is forcibly executed prior to simultaneously processing the reference plane, shaft hole 13, stator cylinder part 14, a corner part 12b as shown in FIG. 2 cannot be thoroughly fabricated to result in a problem of additionally processing corner part 12b later.